There is a fair amount of evidence that published academic papers that make their data publicly available have, on average, a higher number of citations, but ours is the first evidence we know of that attempts to address the causal nature of this relationship. We use the change in editor and the associated dramatic change in enforcement of the data-sharing policy at the American Journal of Political Science and the American Economic Review as instrumental variables for data availability. If assumptions regarding other unobservable factors hold, then our estimate can be interpreted as the causal effect of data sharing on article citations.